Air Cars And Green Fuels
Compressed air cars use the expansion of compressed air to drive the pistons on the engines, it's a very recent alternative car fuel, but it has huge potential. The compressed air is stored in tanks at a high pressure of as much as 4500 pounds per square inch. This high pressure means that the tank has to be of a strong material and yet low in weight. Carbon fiber tanks are used to get the necessary strength and reduce the weight. The capacity of the tank limits the mileage available in such cars and is a severe constraint in its becoming popular. Compressed air cars have virtually zero emission and may be considered as very green cars, though purists challenge this concept because to compress the air electric motors that use power from polluting power stations are a must. So it can only be called fully green if the power sources are also non polluting like wind.
Refueling of the air car requires again filling up the tank with compressed air and this can even be done at home or in a service station. A range of 200 kilometers has been promised by some manufacturers, but they have yet to deliver on this promise. The cost of compressed air engines is reduced substantially because it does not require a cooling system, starters, mufflers and sparkplugs and ignition system.
A compressed air car can be left unused for a long time as unlike electric cars it does not have batteries that will discharge, and the compressed air will continue to remain under pressure even if unused. An added advantage in using compressed air is that the air cools considerably when released from the compression and this can be utilized to air condition the car. The only pollutants that come from air cars are from brake and tire wear. The air cars will also be much lighter.
Costs of running air cars are also very low and due to the simplicity of the technology can be made by less developed countries also. Manufacturers are grappling with the possibility of recovering energy from braking and using it to compress air and add it to the tank.
Besides the harnessing of air which is abundantly available other green fuels also being developed are from algae. Algae can be grown like farming crops are and the algae harvested to produce oil that can easily be used to run cars. The process of growing algae requires almost no inputs and is only dependent on the sun and the few algae that are used to seed the growth. Another green fuel being now looked at is the production of vegetable oil and bio diesel into gasoline. Ethanol production from waste sources and cellulose products is also being examined, as the production of ethanol from agricultural products diverts the use of land from producing food, which is more essential. The recent food crisis is being directly blamed on the diversion of land to corn and corn products for the production of ethanol in the United States.